#include <bits/stdc++.h>

using namespace std;

#define int long long

signed main()
{
    int n;
    string s1 , s2;
    string s;
    cin >> n;
    cin >> s1 >> s2;
    int prev1 = -1 , prev2 = -1 , ret = 0x3f3f3f3f;
    for(int i = 0;i < n;i ++)
    {
        cin >> s;
        if(s == s1)
        {
            if(prev2 != -1)
            {
                ret = min(ret , i - prev2);
            }
            prev1 = i;
        }
        if(s == s2)
        {
            if(prev1 != -1)
            {
                ret = min(ret , i - prev1);
            }
            prev2 = i;
        }
    }
    if(ret == 0x3f3f3f3f) cout << -1 << endl;
    else cout << ret << endl;
    return 0;
}